Can a urine infection in an elderly man cause an abrupt personality change?

Possibly. Urine infections can result in sepsis -- urosepsis. This can result in very serious complications, including personality changes, changes in mentation, altered mental status, or even a coma. Urosepsis in old patients is a serious disease.

Related Questions

Is it possible that a urine infection in a man cause an abrupt personality change?

UTI and personality. It is rare for a man to have a uti, unless he has an anatomical abnormality leading to develop them on a chronic basis. In the absence of that, it is rarer for a UTI to cause a personality change in a male, or anyone else, for that matter.